MANCHESTER -- The 20-story Brady Sullivan office tower has never struck this reporter as being very tall. That all changed Sunday morning in the stairwell of the 10th-floor landing.

Nashua Fire Lt. Bill Campbell, coordinator of the Oct. 6 New Hampshire 9/11 Memorial Stair Climb, met me at the tower Sunday morning for a practice run of 40 stories. Campbell provided a full set of firefighter turnout gear — boots, jacket, pants, helmet and tank apparatus, weighing approximately 60 pounds. Campbell set the mood by describing the conditions firefighters faced on 9/11 at the World Trade Center towers.

"Many of them were carrying tools or hose, that adds to the weight," said Campbell. "They were heading up stairwells, one after the other, while people were streaming past them in the other direction. There was heavy smoke, there was fire, but their adrenaline probably helped push them on."

None of those conditions existed Sunday, though it seemed the heat in the building had been turned up a few degrees. A quick sip of water, and we were off to the stairwell.

Next Sunday, hundreds of firefighters, other emergency responders, families and civilians will walk the stairs 5 1/2 times in the third annual climb, representing the 110 flights of stairs in the twin towers. The event is a fundraiser for the National Fallen Firefighters Foundation and pays tribute to the 343 firefighters killed on Sept. 11, 2001 — many while ascending the twin towers' stairs trying to rescue civilians trapped on the upper floors.

"The stair climb is a way for firefighters and others across the state and region to gather together and tell each other and let the rest of the world know that we will not forget the sacrifices made on that day," Campbell said.

Each participant next Sunday will be given an identity card for one or two firefighters. Climbers will announce each firefighter's name and ring a bell. The cards are still being printed, so Campbell handed me a sheet of paper with the names and pictures of 16 firefighters killed on 9/11.

This was my first stair climb. The equipment gets very heavy, very fast. The sign on the door ahead let us know we'd reached level three. The socks inside the borrowed boots were already squishing from sweat.

Ten more steps. Campbell talked about his memories of the day of the attacks, what they may have been experiencing in the stairwells.

Another 10 steps. Is it possible we're only at the 10th floor? A short pause for breath. At 20 stories, I gasped for air and took in the view of the Millyard and the city beyond.

Then it was down the elevator to the basement, and up the stairs again. Seems like it took a lot longer to reach the fifth floor this time around. On to the 10th floor — 30 stories done. Another break to wheeze a while at 35 stories, before we hit the top again.

There were times along the way where quitting sounded good, as the pain in my knees and shortness of breath increased with each level of altitude. But honestly, looking at the faces of some of those who lost their lives that day, all that swirls through the mind is how can you NOT continue.

There's no fire here.

There's no smoke.

There's no people running down frantically, brushing past you to reach safety outside the tower, while you continue to climb toward God knows what awaits you.

They climbed with tools. They climbed knowing that the cinder block stairwell they were in would likely become their coffin. Every step took them farther from one more birthday, wedding, anniversary, loved one they would never see again.

"As we go forward and get further from that date, you get a lot of people involved who were too young to remember what it was all about," Campbell said. "And then you get a lot of people who talk about where they were the morning of 9/11. That's what it is all about — to never forget it, and to always remember."

Next Sunday's stair climb will get underway at 8:46 a.m. Participants will receive a blessing for the day, observe a moment of silence. Following a brief speech about the event, at 9:03 a.m. — the precise time that United Flight 175 struck the South Tower — a Pipes and Drums band will play "Amazing Grace," and the climb will begin.

"I was there shortly after it happened," said Campbell, a former New York City firefighter who lives in Amherst. At the time of the attacks, he was stationed in the south Bronx, and took part in rescue efforts. "There were about a dozen people who I was friends with, and three who I graduated from training and probationary school with, who lost their lives."

Last year's climb was the only National Fallen Firefighters Foundation (NFFF) stair climb event held in New England; 296 climbers raised over $14,000 for the NFFF.

Those wishing to contribute to this year's event, either by volunteering their time or through a donation, can contact Campbell at bill@nh9-11stairclimb.org. For more information or to register for the climb, visit www.nh9-11stairclimb.org.